Japan says four Chinese government ships intruded into the country's territorial waters near the Senkaku Islands on Thursday morning, and appeared to be following two Japanese fishing boats.
The Japan Coast Guard says the vessels entered the country's territorial waters near Uotsuri Island and Minamikojima one after another between 6:40 a.m. and 7 a.m.
Coast guard officials say the Chinese ships were sailing in the contiguous zone just outside Japan's territorial waters.
The coast guard dispatched patrol vessels to ensure the safety of the fishing boats and to warn the Chinese vessels to leave the territorial waters.
The officials said the four ships were one to two kilometers from the fishing boats that were about 19 kilometers south of Uotsuri Island as of 7 a.m.
This is the eighth time this year that Chinese government ships have been spotted in Japan's territorial waters around the Senkaku Islands.
On Wednesday, two Chinese government ships entered Japanese territorial waters off Minamikojima around 9 a.m. They reportedly remained within the territorial waters for about seven hours.
Japan controls the islands. China and Taiwan claim them. The Japanese government maintains the islands are an inherent part of Japan's territory, in terms of history and international law. It says there is no issue of sovereignty to be resolved over them.